Chair back



FIG. 1 is a front perspective view of the chair back;

FIG. 2 is a back perspective view of the chair back;

FIG. 3 is a right side view of the chair back;

FIG. 4 is a left side view of the chair back;

FIG. 5 is a front view of the chair back;

FIG. 6 is a back view of the chair back;

FIG. 7 is a top view of the chair back; and,

FIG. 8 is a bottom view of the chair back. 

The ornamental design for the chair back, as shown and described. 